Necked-in can body and method for making same

ABSTRACT

A metal container is described. The metal container has a lower portion and an upper portion. The lower portion has an enclosed bottom and a cylindrical sidewall extending upwardly from the enclosed bottom portion. The cylindrical sidewall has a diameter and is centered about a longitudinal axis. The upper portion has a circumferential shoulder portion, a circumferential neck and an open end. The shoulder is integral with an uppermost portion of the cylindrical side wall and is smoothly tapered radially inwardly. The circumferential neck extends upwardly and radially inwardly from an uppermost portion of the circumferential shoulder. The open end is connected to the circumferential neck and has threads for threadable attachment to a closure member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of currentlypending U.S. Design Application. No. 29/262,849, filed Jul. 12, 2006,which is hereby incorporated by reference as if fully set forth herein.

TECHNICAL FIELD

The invention relates to a can body for a two-piece beverage container.More particularly, the present invention is directed to a can bodyhaving a novel necked in upper portion with threads and a method formaking the can body.

BACKGROUND OF THE INVENTION

Two-piece cans are the most common type of metal containers used in thebeer and beverage industry. They are usually formed of aluminum ortin-plated steel. The two-piece can consists of a first cylindrical canbody portion having an integral bottom end wall and a second,separately-formed, top end panel portion which, after the can has beenfilled, is double-seamed thereon to close the open upper end of thecontainer.

An important competitive objective is to reduce the total can weight asmuch as possible while maintaining its strength and performance inaccordance with industry requirements. For pressurized contents such assoft drinks or beer, the end panel must be made of a metal thicknessgauge that is on the order of at least twice the thickness of the sidewall. Accordingly, to minimize the overall container weight the secondend panel should be diametrically as small as possible and yet maintainthe structural integrity of the container, the functionality of the end,and also the aesthetically-pleasing appearance of the can.

Beer and beverage marketers have preferred a neck construction having arelatively smooth neck shape between the opening and the diameter canbody sidewall. This smooth can neck construction was made by a spinnecking process, and apparatus as shown, for example, in U.S. Pat. Nos.4,058,998 and 4,512,172.

More recently, U.S. Pat. No. 5,497,900 described a die necking methodfor necking can bodies. The method of the '900 patent contemplatesforming a cylindrical neck portion adjacent the cylindrical open end ofa container so that the cylindrical neck merged with the cylindricalside wall through a generally smoothly tapered neck portion. The taperedneck portion between the cylindrical neck portion and the cylindricalcontainer side wall initially is defined by a lower, generally arcuatesegment having a relatively large internal curvature at the upper end ofthe cylindrical side wall and an upper, generally arcuate segment havinga relatively large external curvature at the lower end of the reducedcylindrical neck. A further tapered portion is then formed at the openend and is forced downwardly while the cylindrical neck is furtherreduced. The further tapered portion freely integrates with the secondarcuate segment which is reformed and the tapered portion is extended.This process is repeated sequentially until the cylindrical neck isreduced to the desired diameter and a smoothly tapered necked-in portionis formed on the end of the side wall. In each necking operation, thetapered portion is not constrained by the die and is freely formedwithout regard to the specific dimensions of the die transition zone.

The container that is formed by the above die necking process has anaesthetically-pleasing appearance, greater strength and crush resistanceand is devoid of the scratches or wrinkles in the neck produced in aspin necking operation. Similar methods are still used today.

More recently, metal beer and beverage containers have produced metalcans to resemble glass bottles. U.S. Pat. Nos. 5,293,765 and 5,822,843disclose methods and apparatuses for manufacturing threaded aluminumcontainers which resemble bottles.

One of the drawbacks of producing metal bottles is that the containermanufacturer must build new facilities to produce the metal bottle orretrofit current facilities with new tooling to manufacture the metalbottles. Furthermore, the metal bottles are purported to use more thanthree times the metal used to make an aluminum can.

The present invention is provided to solve the problems discussed aboveand other problems, and to provide advantages and aspects not providedby prior metal bottles of this type. A full discussion of the featuresand advantages of the present invention is deferred to the followingdetailed description, which proceeds with reference to the accompanyingdrawings.

SUMMARY OF THE INVENTION

One embodiment of the present invention is directed to a metalcontainer. The metal container comprises a lower portion and an upperportion. The lower portion comprises an enclosed bottom and acylindrical sidewall extending upwardly from the enclosed bottom portionhaving a diameter. The cylindrical sidewall is centered about alongitudinal axis. The upper portion comprises a circumferentialshoulder portion, a circumferential neck, and an open end. Thecircumferential shoulder portion is integral with an uppermost portionof the cylindrical side wall. The circumferential shoulder is smoothlytapered radially inwardly and has a radius of curvature greater than0.500 inches (1.27 cm). The circumferential neck extends upwardly andradially inwardly from an uppermost portion of the circumferentialshoulder. The open end is connected to the circumferential neck. Theopen end has threads for threadable attachment to a closure member.

In one aspect the first embodiment, circumferential neck issubstantially flat.

In another aspect of the first embodiment, a transition region betweenthe circumferential shoulder and the circumferential neck issubstantially flat.

In another aspect of the first embodiment, a height of the upper portionis less than 2.6 inches (6.6 cm).

In another aspect of the first embodiment, a height of the metalcontainer is less than 6.3 inches (16.0 cm).

In another aspect of the first embodiment, the radius of curvature ofthe circumferential shoulder is between 0.500 inches (1.27 cm) and 1.500inches (3.81 cm).

In another aspect of the first embodiment, the radius of curvature ofthe circumferential shoulder is between 0.500 inches (1.27 cm) and 1.100inches (2.79 cm).

In another aspect of the first embodiment, the radius of curvature ofthe circumferential shoulder is about 1.00 inches (2.54 cm).

In another aspect of the first embodiment, the radius of curvature ofthe circumferential shoulder is about 0.62 inches (1.57 cm).

In another aspect of the first embodiment, the angle of thecircumferential neck is between 20 and 37 degrees.

In another aspect of the first embodiment, the angle of thecircumferential neck is about 22 degrees.

In another aspect of the first embodiment, the angle of thecircumferential neck is about 35 degrees.

In another aspect of the first embodiment, the upper portion furthercomprises a second circumferential shoulder portion integral with anuppermost portion of the circumferential neck. The secondcircumferential shoulder has a lower concave bend joined to an upperconvex bend by an upwardly extending intermediate segment.

In another aspect of the first embodiment, the second circumferentialneck is directly connected to the open end.

In another aspect of the first embodiment, the circumferential neckcomprises a first radially compressed tapered portion having a singlecompressed lower segment, and a second further radially compressedtapered portion extending from an upper part of the first taperedportion. The second tapered portion is disposed between the firsttapered portion and the open end of the metal container.

In another aspect of the first embodiment, metal container furthercomprises a containment space for holding a liquid. The containmentspace has a volume of at least 10 ounces (0.30 liters).

In another aspect of the first embodiment, the metal container furthercomprises a containment space for a holding a liquid. The containmentspace has a volume of at least 14 ounces (0.41 liters).

A second embodiment of the present invention is directed to a metalcontainer. The metal container comprises a lower portion and an upperportion. The lower portion comprises an enclosed bottom and acylindrical sidewall extending upwardly from the enclosed bottom portionhaving a diameter. The cylindrical sidewall is centered about alongitudinal axis. The upper portion comprises a circumferentialshoulder, a substantially flat circumferential neck, and an open end.The circumferential shoulder portion is integral with an uppermostportion of the cylindrical side wall. The circumferential shoulder issmoothly tapered radially inwardly and has a radius of curvature greaterthan 0.500 inches (1.27 cm). The substantially flat circumferential neckis integral with an uppermost portion of the circumferential neck. Theneck extends upwardly and radially inwardly from an uppermost portion ofthe circumferential shoulder, wherein a transition region between theneck and the shoulder is substantially flat. The open end is connectedto the circumferential neck. The open end has threads for threadableattachment to a closure member.

A third embodiment of the present invention is directed to a metalcontainer. The metal container comprises a lower portion and an upperportion. The lower portion comprises an enclosed bottom and acylindrical sidewall extending upwardly from the enclosed bottom portionhaving a diameter. The cylindrical sidewall is centered about alongitudinal axis. The upper portion comprises a circumferentialshoulder, a circumferential neck, and an open end. The circumferentialshoulder portion is integral with an uppermost portion of thecylindrical side wall. The circumferential shoulder is smoothly taperedradially inwardly and has a radius of curvature greater than 0.500inches (1.27 cm). The circumferential neck extends upwardly and radiallyinwardly from an uppermost portion of the circumferential shoulder. Theopen end is connected to the circumferential neck. The open end havingthreads for threadable attachment to a closure member. The upper andlower portions define a containment space for holding between about 10(0.30 liters) and about 14 ounces (0.41 liters) of liquid.

Another embodiment of the present invention is directed to a method andapparatus for producing the containers described herein.

Other features and advantages of the invention will be apparent from thefollowing specification taken in conjunction with the followingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a threaded can body of the presentinvention;

FIG. 2 is a cross-sectional view of the threaded can body of FIG. 1;

FIG. 3 is a partial cross-sectional view of a segment of the upperportion of a threaded can body;

FIG. 4 is a cross-sectional view of an alternative embodiment of athreaded can body;

FIG. 5 is a partial cross-sectional view of a segment of the upper endof the threaded can body of FIG. 4;

FIG. 6 is a cross-sectional view of an alternative thread arrangementfor use in conjunction with the threaded can bodies of FIGS. 2 and 4;

FIG. 7 is a flowchart depicting a method of forming a can body accordingto an aspect of the present invention;

FIG. 8 is a schematic of a can body forming process according to oneaspect of the present invention;

FIG. 9 is an illustration of necking procedure utilized in forming a canbody of the present invention; and

FIG. 10 a second illustration of a necking procedure utilized in forminga can body of the present invention.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiments illustrated.

The present invention is directed to two-piece metal containers havingthreads for threadable attachment of a closure member, such as athreaded cap, to the open end of the metal container.

It is believed that advantages of the metal containers described hereinare increased strength through geometric design and improved processingby allowing existing manufacturing facilities to, for the most part,process the threaded metal containers. The applicants further believethat the container described herein has an aesthetically-pleasingappearance, greater strength, and crush resistance. Metal usage may alsobe reduced by increasing the strength of the container so that requiredstrength is achieved through geometric design rather than increasedmetal volume, especially thickness. Metal usage is is further decreasedby decreasing the size of the open end thereby decreasing the size ofthe can end required to seal the open end.

Referring to FIGS. 1-6, embodiments of the present invention areillustrated. Generally, the containers 10 of the present invention havea lower portion 12 and an upper portion 14. The upper and lower portionsdefine a containment space for holding between about 8 ounces (0.24liters) and about 16 ounces (0.48 liters) of liquid, preferably about 10ounces (0.30 liters) and about 14 ounces (0.41 liters), more preferably9 ounces (0.27 liters) and 14 (0.41 liters), and most preferably 9.8ounces (0.29 liters) to 13.6 ounces (0.408 liters), or any range orcombination of ranges therein.

The lower portion 12 includes an enclosed bottom 16 and a cylindricalsidewall 18 extending upwardly from the enclosed bottom portion 16.

The bottom 16 has a dome-shaped center panel 17 surround by a generallya circumferential annular support 20. An outer wall 22 extends radiallyoutwardly and upwardly relative to the annular support 20 and joins thebottom 16 with the lowermost portion of the cylindrical sidewall 18.

The cylindrical sidewall 18 is centered about the longitudinal axis 24.In the embodiments illustrated the sidewall 18 is smooth and flat.However, one ordinary skilled in the art would appreciated that any oneof a number of forming techniques could be employed to impart a shapeand/or texture to the sidewall 18. For instance, the interior of thesidewall 18 could be forced outwardly by a fluid pressure or formingsegments, laser treatment could be employed to etch or otherwise markthe sidewall 18, and/or flutes or other designs may be imparted onto thesidewall 18 through mechanical deformation of the sidewall 18.

The upper portion 14 includes a circumferential shoulder portion 26. Theshoulder 26 has a convexly curved appearance when viewed from a vantagepoint external to the container 10. The shoulder 26 has a lowermostpoint integral with an uppermost portion of the cylindrical sidewall 18.The transition point between the sidewall 18 and shoulder 26 is at apoint where the can body 10 begins to curve radially inwardly. Statedanother way, the diameter of the container body 10 begins to decrease atthe point where the shoulder 26 begins and the sidewall 26 ends.

It is believed that the radius of curvature of the shoulder 26 isimportant for the aesthetic appearance of the container 10 as well asfor the strength of the container 10. It is further believed that thesecharacteristics differentiate the present embodiments for prior artcontainers of this type. For instance, in the embodiments illustrated, aradius of curvature of the shoulder R_(S) is greater than 0.500 inches(1.27 cm), preferably 0.500 (1.27 cm) to 1.500 inches (3.81 cm), morepreferably 0.500 inches (1.27 cm) to 1.100 inches (2.79 cm). In theembodiment illustrated in FIGS. 1-3, the radius of curvature R_(S) is1.000 inches±0.010 inches (2.54 cm±0.0254 cm). In the embodimentillustrated in FIGS. 4 and 5, the radius of curvature R_(S) is 0.0620inches±0.010 inches (1.57 cm±0.0254 cm). One ordinary skilled in the artof metal container design would recognize that the radius of curvatureR_(S) could fall within these ranges, or any combination within theseranges without departing form the spirit of the invention.

The shoulder 26 has a smoothly tapered appearance. This appearance isachieved through a die forming technique similar to the die formingtechnique disclosed in commonly assigned U.S. Pat. No. 5,497,900 whichis hereby incorporated by reference as if fully set forth herein. Thesmoothly tapered appearance differs from containers produced usingalternative methods like spin-necking in that the radius of curvature ismuch greater so that wrinkles and scratches are avoided as is theunsightliness of an abrupt reduction in the diameter of the containercaused by a sharp corner or bend at the shoulder. Thus, a verticallength of the shoulder 26, parallel to the longitudinal axis, is greaterthan the vertical length of shoulders produced through other formingtechniques.

The upper portion 14 further includes an inwardly taperedcircumferential neck 28. The neck 28 has a lowermost portion integralwith an uppermost portion of the shoulder 26. Thus, the neck 28functions to further decrease the diameter of the container 10 along thevertical length of the neck 28. The neck 28 is preferentiallysubstantially flat, i.e. primarily free of an arc-shape design, althoughit may have some discontinuity formed during production. An angle θ ofthe neck 28, measured from a vertical axis parallel to the longitudinalaxis, is greater than 10 degrees, preferably 15 to 60 degrees, and morepreferably 20 to 37 degrees. The embodiment illustrated in FIGS. 1-3 hasan angle θ of 35 degrees±1.5 degrees, and the embodiment illustrated inFIGS. 4 and 5 has an angle θ of 22 degrees±1.5 degrees. One ordinaryskilled in the art of container design would appreciate that that theangle θ of the neck 28 could fall within these ranges, or anycombination within these ranges without departing from the spirit of theinvention. Like the radius of curvature of the shoulder 26, the angle θof the neck 28 contributes to the novelty and non-obvious (i.e.inventive) nature of the embodiments disclosed herein.

The upper portion 14 also includes a second circumferential shoulder 30located above the neck 28. This second shoulder 30 is integral with anuppermost portion of the neck 28. This shoulder 30 has a lower concavebend joined to an upper convex bend by an upwardly extendingintermediate segment 32. Thus, the second shoulder 30 extends the heightof the container 10 as it further decreases the diameter of thecontainer 10, though to a lesser extent than the first shoulder 26.

The upper portion 14 further includes an open end 34. The open end 34has a thread arrangement 36 for attachment to a closure member, such asa cap. The thread arrangement 36 includes a capper clearance 38 integralwith an uppermost portion of the second shoulder 30. The capperclearance 38 receives a radially innermost portion of a cap threadablyattached to the container utilizing the thread arrangement 36.

A threaded portion 40 is integral with an uppermost portion of thecapper clearance 38. The threaded portion 40 includes a male thread 42having a thread pitch of about 0.125±005 inches. The male thread 42 hasupper and lower thread angles φ₁,φ₂. The upper thread angle φ₁ ismeasured upwardly from a horizontal axis. The upper thread angle φ₁ isgenerally between 30 degrees and 70 degrees, more preferably betweenabout 33 degrees to about 60 degrees, and most preferably either 34degrees±0.5 degrees as illustrated in FIGS. 3 and 5 or 55 degrees±0.5degrees as illustrated in FIG. 6. The lower thread angle φ₂ is measureddownwardly from the horizontal axis. The lower thread angle φ₂ may beequal to the upper thread angle φ₁ or greater than or less than theupper thread angle φ₁, but is preferably between 30 degrees and 70degrees, more preferably about 33 degrees to about 49 degrees, and mostpreferably either 46 degrees±0.5 degrees as illustrated in FIGS. 3 and 5or 48 degrees±0.5 degrees as illustrated in FIG. 6. The threaded portion40 terminates at a radially inwardly tapered portion 44. One ordinaryskilled in the art would appreciate that these angles φ₁,φ₂ may fallwithin these stated ranges or within any combination of theses statedranges without departing from the spirit of the invention.

The container opening 46 is defined by a curl 48. The curl 48 has anupper surface 50 which may be curved as shown if FIGS. 3 and 5.Alternatively, the upper surface 50 may have a flat substantiallyhorizontal surface 50 for cooperative sealing with a cap. This uppersurface 50 is annular and is generally 0.080±0.005 inches wide. Theopening 46 is less than 1.0 inch (25.4 mm) in diameter, typically 0.70to 1.0 inches (17.8 to 25.4 mm), preferably 0.75 to 0.95 inches (19.1 to24.1 mm), more preferably 0.80 to 0.90 inches (20.3 to 22.9 mm), andmost preferably 0.80±0.010 (20.3±0.25 mm), or any range or combinationof ranges therein.

Referring to FIGS. 7 and 8, can bodies of the present invention areproduced from the second circumferential neck down in conventional canbody manufacturing process 100. For instance, flat aluminum sheet isdelivered to a cupper station 116, e.g. paid off from aluminum coils ordelivered as multiple aluminum disks 104 from a disk feeder. The cupperstation 116 deforms the aluminum sheet in a drawing process to form ashallow cup 120. Once complete, the shallow cups 120 drop from thecupper station 116 onto a cup conveyor for transfer to the next station.

The shallow cups 120 are transferred continuously to one or morebodymaker stations 124. Each bodymaker station 124 includes tooling fordrawing and thinning the shallow cups 120 to form thin-walled tubularcan bodies 128 having an open end and an opposing closed end. Eachbodymaker station 124 contains a tool called a punch, which forms theshape of the can body 128 by forcing the cup 120 through a series ofprogressively smaller circular ironing rings. This action draws themetal up the sides of the punch, ironing it into a can body 128. As thecup 120 is forced through the rings, its diameter is reduced, its wallsare thinned and its height is increased. At the end of the punch stroke,the bottom is formed into a dome shape that strengthens the bottom ofthe can body 128. During this process, referred to as wall ironing, themetal must be lubricated to reduce frictional heat.

The thin-walled, tubular can bodies 128 are transferred from thebodymakers 124 to trimmer stations 132. The trimmer station includes aknife for shearing excess material about the open ends of the tubularcan bodies 128. This process adapts the can bodies 128 to a uniform,predetermined height.

The can bodies 128 are then continuously transferred to a washer station140. The washer 136 removes the forming lubricants before theapplication of outside decoration (or label) and inside protectivecoating. The washed can bodies are discharged through a dryer station144 where the can bodies 128 are dried with forced hot air.

Depending on end user requirements, a base layer of coating can beapplied to the outer surface of the can bodies 128 at a base coaterstation 148. The base coating layer is generally a white or clear basecoat. A base coat dryer station 152 may be provided for curing the basecoat layer.

The can bodies 128 are then continuously transferred to a decorativecoating station 156. The decorative coating station 156 applies adecorative layer of coating (ink) to the outer surface of thethin-walled tubular can bodies 128. The inked can bodies 128 move to arotating varnish application roll that applies a clear coating over theentire outer sidewall. The clear coating protects the ink fromscratching and contains lubricants that facilitate can conveying.

The can bodies 128 are transferred from the decorator 156 onto a pin (sothat only the inside surface is contacted) and is conveyed through adecorator coating, or “pin,” oven/drier station 160 where the ink isdried with forced hot air.

Following application and curing of the exterior decorative layer, thecan bodies 128 are conveyed to an inner surface coater station 164. Thisstation 164 includes a bank of spray machines that spray the innersurfaces of the can bodies 128 with an epoxy-based organic protectivecoating. The inside coating is also cured by forced hot air at anotherdryer station 168. The coating prevents the beverage from contacting orreacting with the metal of the inner surface of the can body 128.

The can bodies may be palletized at this point and transferred toanother location or separate manufacturing line for further processing.Alternatively, the can bodies can continue to be processed in-line. Ineither case, the processing continues as described below.

After the can bodies 128 leave the drier station 168, they pass througha lubricator station that applies a thin film of lubricant to theexterior of the top (open end) where a neck and a flange will be formed.A necker station 176 reduces the diameter of the open ends of the canbodies 128, and gives the cans the characteristic neck shape. Here, thediameter of the top of the can is reduced or “necked-in.” The neckingstation includes a plurality of necking modules.

At each module, an open end of the unfinished can body is necked-in orthe inwardly-tapered portion is reshaped. A small overlap is createdbetween a previously necked-in portion while the overall necked-inportion is extended and axially enlarged and small segments of reductionare taken so that the various operations blend smoothly into thefinished necked-in portion. The resultant necked-in portion has arounded shoulder on the end of the cylindrical side wall which mergeswith an inwardly-tapered annular straight neck segment through anarcuate portion, as described above. The opposite end of the annularstraight segment merges with the open end through a second arcuatesegment.

Prior to this stage of the processing, the unfinished can body has athickened portion adjacent its upper open end. As the open end of thecontainer is moved into engagement with a necking die, the forming anglein the die results in large radial forces on the container wall andsmall axial forces so that there is radial compression of the wall ofthe container.

As illustrated in FIGS. 9 and 10, as the can body is moved upwardly intothe necking die as depicted on the right-hand side of FIG. 9, thediameter of the container neck is reduced and a slight curvature 211 isformed on the container body between the reduced cylindrical neck 212and the container side wall 210.

The left side portion of FIG. 9 shows a container 10 being movedupwardly into a necking die 130A. As the open end of the container 10 ismoved into engagement with the die, the forming angle in the die resultsin large radial forces on the container wall and small axial forces sothat there is radial compression of the wall of the container, as willbecome clear.

FIG. 9 shows a necking die 130A having a first cylindrical wall portion202 a, a transition zone surface 204, and a second cylindrical wallportion 205. The first cylindrical wall portion 202 a has a diameterapproximately equal to the external diameter of the container 10 with aclearance of about 0.006 inch. The second cylindrical wall portion 205has a reduced diameter equal to the external diameter of the reducedneck that is being formed in the first necking operation.

The transition zone or intermediate surface 204 has a first arcuatesurface segment A1 at the end of the first cylindrical wall portion 202which has a radius of about 0.220 inch and a second arcuate surfacesegment R1 at the end of the second cylindrical wall portion 205 whichhas a radius of about 0.120 inch.

As the container 10 is moved upwardly into the die element 130A, asdepicted on the right-hand side of FIG. 9, the diameter of the containerneck is reduced and a slight curvature 211 is formed on the containerbody between the reduced cylindrical neck 212 and the container sidewall 210.

In the first necking module, the diameter of the container 10 is reducedonly a very small amount while the portion of the can body to be neckedis conditioned for subsequent operations. In other words, a form controloperation is performed on the ultimate neck portion to prepare thecontainer for subsequent operations.

This is accomplished by tightly controlling the dimensions andtolerances of reduced cylindrical surface 205 of die 130A and theexternal surface diameter of the forming sleeve or element 150A. Theexternal diameter of sleeve or element 150A is equal to the internaldiameter of cylindrical surface 205 less two times the thickness of thecontainer side wall (t) with a maximum of 10% clearance of the wallthickness. By thus tightly controlling these dimensions, dents orimperfections in the container are removed or minimized, and also anyvariations in wall thickness around the perimeter of the neck arereduced to provide concentricity of the side wall of the container withthe die.

Also, as mentioned above, during the movement of container 10 from theposition illustrated at the left of FIG. 9 to the position at the rightof FIG. 9, pressurized air may be introduced into the container 10 topressurize it, if considered necessary, and thereby temporarilystrengthen the container 10. This air is used primarily to strip thecontainer from the necking die 130A after the necking operation iscompleted. As explained above during the upward movement of thecontainer 16, the forming control member 140A and forming sleeve orelement 150A are moved upwardly slightly faster than the container 10 toaid in drawing or pulling the metal of the container wall into the die.

At the first forming station, the die element 130A forms the container10 to have a shoulder 211 between a cylindrical side wall 210 and areduced cylindrical neck 212; the shoulder 211, at this point, includesfirst and second arcuate segments CA1, CR1, respectively.

After the first necking operation is completed, the partially-neckedcontainer 10 exits therefrom and is fed to the second necking module. Inthe second necking operation, the necked-in portion is axially elongatedwhile the reduced cylindrical neck portion 212 is further reduced indiameter by compression of the metal therein. This is accomplished by asecond necking die 130B (FIG. 10) that has a transition zone 222 betweena cylindrical first surface 202 b, which has the same internal diameteras the external diameter of the container, and a reduced cylindricalsurface 226 at the upper end thereof. The transition zone 222 has afirst arcuate surface segment A2 integral with the cylindrical wallsurface 202 b and a second arcuate surface segment R2 integral with thereduced diameter cylindrical surface 226.

Referring to FIG. 10, the surface 222 of die element 130B of the secondnecking station initially engages the upper edge of the container 10with arcuate die surface R2 at a small acute forming angle.

As the container is moved from the left-hand position, shown in FIG. 10,to the right-hand position, the original tapered portion is axiallyelongated to further form a shoulder 228 having arcuate segments CA2,CR2 while the neck 212 is reduced to a further reduced diameter, asshown at 229.

In the second necking operation, the diameter of the reduced cylindricalneck is reduced, while the metal is further radially compressed therein.In the second necking die 130B, the forming angle described above isdefined by the arcuate surface segment R2. It will be noted that thelower segment of the shoulder adjacent the cylindrical sidewall remainssubstantially unchanged while the upper part is reformed and the taperedportion is axially elongated.

During the second operation, a second tapered portion is essentiallyfreely formed in the reduced cylindrical neck being free of the die atits lower end and this second tapered portion is forced along thereduced neck portion until it integrates with the arcuate segment CR1 ofthe first tapered portion. During this second operation, the lower partof the first tapered portion remains essentially unchanged while thesecond tapered portion combines and blends with the first taperedportion to produce an extension thereof and part of the finishedshoulder.

It will be appreciated that the necking operation performed at each ofthe various modules is somewhat repetitive. It should be appreciatedthat, in fact, each module performs a part, and not all, of thenecked-in portion while the cylindrical neck is sequentially andprogressively reduced in diameter. That is, each module adds to and atleast partially reforms and extends the necked-in portion produced onthe container by the previous operation.

At each subsequent station, the cylindrical neck is compressed andreduced while the existing tapered or necked-in portion is partiallyreformed and axially elongated or extended to produce a small annularinwardly-tapered portion between the upper and lower arcuate segmentsdescribed above.

Thus, the necking operation forms a smooth tapered necked-in portionbetween the container side wall and the reduced diameter cylindricalneck. This necked-in portion or taper includes a first arcuate segmentintegral with the side wall and a second arcuate segment integral withthe reduced cylindrical neck. During the necking operation, the neck,comprising the reduced diameter cylindrical neck and the necked-inportion, is formed in segments while the axial dimension is increasedand the cylindrical neck is further reduced in diameter and in axiallength while a rounded shoulder is formed at the end of the side wall.At the same time, a straight tapered wall section or segment is createdin the necked-in or tapered portion.

In each of the necking modules, the principal forces applied to theupper portion of the can body, which includes the first shoulder, thetapered neck, and the open end, are radially inwardly-directed forcesand therefore the metal is primarily compressed and localized bending isminimized. The tapered portion is allowed to determine its profilebecause it is not constrained by the die below the contact area and isthus not dependent on the configuration of the lower portion of thetransition zone of the die. Of course, the forming sleeve or element 150will direct the upper edge of the container 16 into the annular slotdefined between the forming sleeve or element and the reducedcylindrical portion of the die 130. Stated another way, the formingelement 150 which engages the inner surface of the container 16 providesa guiding function or form control function.

The resultant can body comprises a cylindrical side wall extending froman integral bottom end wall, a single smooth necked in shoulder portionat an end of the cylindrical side wall, a single inwardly taperedannular straight segment extending from the shoulder between thesidewall and an open end of the can body. The inwardly tapered annularstraight segment comprises a first radially compressed tapered portionhaving a single compressed lower segment, and a second further radiallycompressed tapered portion extending from an upper part of the firsttapered portion. The second tapered portion is disposed between thefirst tapered portion and the open end. Subsequent necking modules wouldresult in additional tapered portions. Thus, a plurality of taperedportions will be produced, preferably between 18 and 39. More preferablya trim operation occurs after an eighteenth necking operation; a secondtrim operation and an expansion operation are carried out after thethirty-first necking operation; threads are produced in a threadingoperation after a thirty-fifth necking operation, and the end curl isprovided in a curling operation which takes place after a thirty-ninthnecking operation. This is all done on the necking station as acontinuous sequence.

As stated before, method can be carried out on-line for a continuoussequence from cupping to finished threaded can body. Alternatively, thecan bodies of the present invention are not flanged at the neckingstation, and may be removed from the typical process after the dryingstation 168.

While the specific embodiments have been illustrated and described,numerous modifications come to mind without significantly departing fromthe spirit of the invention, and the scope of protection is only limitedby the scope of the accompanying Claims.

1. A metal container, the metal container comprising: a lower portioncomprising: an enclosed bottom; and a cylindrical sidewall extendingupwardly from the enclosed bottom portion having a diameter, thecylindrical sidewall centered about a longitudinal axis; and an upperportion comprising: a circumferential shoulder portion integral with anuppermost portion of the cylindrical side wall, the circumferentialshoulder smoothly tapered radially inwardly; a circumferential neckextending upwardly and radially inwardly from an uppermost portion ofthe circumferential shoulder; and an open end connected to thecircumferential neck, the open end having threads for threadableattachment to a closure member.
 2. The metal container of claim 1wherein the circumferential shoulder has a radius of curvature greaterthan 0.500 inches (1.27 cm).
 3. The metal container of claim 1 whereinthe circumferential neck is substantially flat.
 4. The metal containerof claim 1 wherein a transition region between the circumferentialshoulder and the circumferential neck is substantially flat.
 5. Themetal container of claim 1 wherein a height of the upper portion is lessthan 2.6 inches (6.6 cm).
 6. The metal container of claim 1 wherein aheight of the metal container is less than 6.3 inches (16.0 cm).
 7. Themetal container of claim 1 wherein a radius of curvature of thecircumferential shoulder is between 0.500 inches (1.27 cm) and 1.500inches (3.81 cm).
 8. The metal container of claim 1 wherein a radius ofcurvature of the circumferential shoulder is between 0.500 inches (1.27cm) and 1.100 inches (2.79 cm).
 9. The metal container of claim 1wherein a radius of curvature of the circumferential shoulder is about1.00 inches (2.54 cm).
 10. The metal container of claim 1 wherein aradius of curvature of the circumferential shoulder is about 0.62 inches(1.57 cm).
 11. The metal container of claim 1 wherein the angle of thecircumferential neck is between 15 and 60 degrees.
 12. The metalcontainer of claim 1 wherein the angle of the circumferential neck isbetween 20 and 37 degrees.
 13. The metal container of claim 1 whereinthe angle of the neck is about 22 degrees.
 14. The metal container ofclaim 1 wherein the angle of the neck is about 35 degrees.
 15. The metalcontainer of claim 1 wherein the upper portion further comprises asecond circumferential shoulder portion integral with an uppermostportion of the circumferential neck, the second circumferential shoulderhaving a lower concave bend joined to an upper convex bend by anupwardly extending intermediate segment.
 16. The metal container ofclaim 14 wherein the second circumferential neck is directly connectedto the open end.
 17. The metal container of claim 1 wherein thecircumferential neck comprises a first radially compressed taperedportion having a single compressed lower segment, and a second furtherradially compressed tapered portion extending from an upper part of thefirst tapered portion, the second tapered portion disposed between thefirst tapered portion and the open end of the metal container.
 18. Themetal container of claim 1 further comprising a containment space forholding a liquid, the containment space having a volume of about 10ounces (0.30 liters).
 19. The metal container of claim 1 furthercomprising a containment space for a holding a liquid, the containmentspace having a volume of about 14 ounces (0.41 liters).
 20. A metalcontainer, the metal container comprising: a lower portion comprising:an enclosed bottom; and a cylindrical sidewall extending upwardly fromthe enclosed bottom portion having a diameter, the cylindrical sidewallcentered about a longitudinal axis; and an upper portion comprising: acircumferential shoulder portion integral with an uppermost portion ofthe cylindrical side wall, the circumferential shoulder smoothly taperedradially inwardly and having a radius of curvature greater than 0.500inches (1.27 cm); a substantially flat circumferential neck integralwith an uppermost portion of the circumferential neck, the neckextending upwardly and radially inwardly from an uppermost portion ofthe circumferential shoulder, wherein a transition region between theneck and the shoulder is substantially flat; and an open end connectedto the circumferential neck, the open end having threads for threadableattachment to a closure member.
 21. A metal container, the metalcontainer comprising: a lower portion comprising: an enclosed bottom;and a cylindrical sidewall extending upwardly from the enclosed bottomportion having a diameter, the cylindrical sidewall centered about alongitudinal axis; and an upper portion comprising: a circumferentialshoulder portion integral with an uppermost portion of the cylindricalside wall, the circumferential shoulder smoothly tapered radiallyinwardly and having a radius of curvature greater than 0.500 inches(1.27 cm); a circumferential neck extending upwardly and radiallyinwardly from an uppermost portion of the circumferential shoulder, andan open end connected to the circumferential neck, the open end havingthreads for threadable attachment to a closure member; wherein the upperand lower portions define a containment space for holding between 9ounces (0.27 liters) and 14 ounces (0.41 liters) of liquid.